Physical blowing agents for polyurethanes

Abstract

Polyurethane foam materials are the majority among all foam materials. Additionally, they are main part of all produced polyurethanes. Therefore, the problem of selection of suitable blowing agents is very crucial from the point of view of technological, economic and environmental protection benefits. The work is collected and discussed all kinds of physical blowing agents which are used in the production of polyurethane foams. The basic blowing agents used in the polyurethane technology include: chlorofluorocarbons (CFCs), hydrogenated fluorocarbons (HFCs), hydrogenated chlorofluorocarbons (HCFCs), low-boiling saturated and unsaturated hydrocarbons, hydrofluoroethers (HFEs) and carbon dioxide. Issues related to the problem of selecting a suitable foaming agent, taking into account the environmental impacts, foam production costs and the impact on their properties, especially on the heat-insulation, combustibility, have been widely discussed in the work.

New amine adducts with carbon dioxide as blowing agents in the production of integral polyurethane foams

“…Adducts containing 13.8 wt % carbon dioxide that were released in the foaming process were obtained [31]. A broad review of foaming agents also taking into account carbon dioxide adducts was presented by Wiankowski and co-authors [32]. The analyzes presented in the article confirm the possibilities and the need for further work on blowing agents for polyurethane foams, because of the arising question: Will the fourth generation of foaming agents used in industrial practice prove themselves after many years of using them in practice in extremely drastic conditions?.…”

Effect of Crosslink Density on Thermal Aging of Bio-Based Rigid Low-Density Closed-Cell Polyurethane Foams

“…Current research and development in polyurethane (PU) foams allows researchers and engineers to respond to these challenges by both increasing the energy efficiency of the structures by incorporating PU foams in the thermal insulation envelope 1,2 and by increasing the relative amount of renewable materials in the foams 3 produced by employing blowing agents (BAs) with low global warming potential. 4,5 Closed-cell low-density PU foams are mainly applied as a thermal insulation material; therefore, thermal conductivity of foams and its change with time are of primary importance. Thermal conductivity of rigid high-porosity closed-cell PU foams is affected by both foam morphology and the cell gas composition, and the high volume fraction of the physical BA (PBA) in it ensures low initial conductivity.…”

“…Concerns for the environment and sustainable management of renewable resources are becoming increasingly important drivers for developments in the chemical industry. Current research and development in polyurethane (PU) foams allows researchers and engineers to respond to these challenges by both increasing the energy efficiency of the structures by incorporating PU foams in the thermal insulation envelope , and by increasing the relative amount of renewable materials in the foams produced by employing blowing agents (BAs) with low global warming potential. , …”

Rigid polyurethane foam composites with nut shells

“…Wide possibilities of modification within the raw material contents and adjusting the synthetic procedures allow for preparation of products suitable for construction, automotive, furniture, clothing and packaging applications as well as in cosmetics indus-try or medicine [1,2]. High demand for the polyurethane materials and the growing ecological awareness lead to the quest for novel eco-friendly solutions for raw materials [3,4]. Moreover, apart from the desired limitation of the petrochemical raw material consumption, another relevant issue is related to the utilisation of the large amounts of waste generated during the industrial-scale food production [2,5,6].…”